setpwent

       #include <sys/types.h>
       #include <pwd.h>

       struct passwd *getpwent(void);

       void setpwent(void);

       void endpwent(void);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       getpwent(), setpwent(), endpwent():
           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
           _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED

DESCRIPTION
       The getpwent() function returns a pointer to a structure containing the
       broken-out  fields  of  a  record from the password database (e.g., the
       local password file /etc/passwd, NIS, and LDAP).  The first time  getp-
       went()  is  called,  it returns the first entry; thereafter, it returns
       successive entries.

       The setpwent() function rewinds to the beginning of the password  data-
       base.

       The  endpwent()  function  is used to close the password database after
       all processing has been performed.

       The passwd structure is defined in <pwd.h> as follows:

           struct passwd {
               char   *pw_name;       /* username */
               char   *pw_passwd;     /* user password */
               uid_t   pw_uid;        /* user ID */
               gid_t   pw_gid;        /* group ID */
               char   *pw_gecos;      /* user information */
               char   *pw_dir;        /* home directory */
               char   *pw_shell;      /* shell program */
           };

       When  shadow(5)  passwords  are  enabled  (which  is  default  on  many
       GNU/Linux  installations)  the content of pw_passwd is usually not very
       useful.  In such a case most passwords are stored in a separate file.

       The variable pw_shell may be empty, in which case the system will  exe-
       cute the default shell (/bin/sh) for the user.

       For more information about the fields of this structure, see passwd(5).

RETURN VALUE
       The  getpwent()  function  returns  a pointer to a passwd structure, or
       NULL if there are no more entries or an error occurred.   If  an  error
       occurs,  errno is set appropriately.  If one wants to check errno after
       the call, it should be set to zero before the call.

       ENFILE The system-wide limit on the total number of open files has been
              reached.

       ENOMEM Insufficient memory to allocate passwd structure.

       ERANGE Insufficient buffer space supplied.

FILES
       /etc/passwd
              local password database file

ATTRIBUTES
       For  an  explanation  of  the  terms  used   in   this   section,   see
       attributes(7).

       +------------+---------------+-----------------------------+
       |Interface   | Attribute     | Value                       |
       +------------+---------------+-----------------------------+
       |getpwent()  | Thread safety | MT-Unsafe race:pwent        |
       |            |               | race:pwentbuf locale        |
       +------------+---------------+-----------------------------+
       |setpwent(), | Thread safety | MT-Unsafe race:pwent locale |
       |endpwent()  |               |                             |
       +------------+---------------+-----------------------------+
       In  the  above  table, pwent in race:pwent signifies that if any of the
       functions setpwent(), getpwent(), or endpwent() are used in parallel in
       different threads of a program, then data races could occur.

CONFORMING TO
       POSIX.1-2001,  POSIX.1-2008,  SVr4,  4.3BSD.  The pw_gecos field is not
       specified in POSIX, but is present on most implementations.

SEE ALSO
       fgetpwent(3), getpw(3), getpwent_r(3), getpwnam(3), getpwuid(3),  putp-
       went(3), shadow(5), passwd(5)

COLOPHON
       This  page  is  part of release 4.04 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest     version     of     this    page,    can    be    found    at
       http://www.kernel.org/doc/man-pages/.

GNU                               2015-12-28                       GETPWENT(3)
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